Methods for depositing tungsten layers employing atomic layer deposition techniques

ABSTRACT

A method for forming a tungsten layer on a substrate surface is provided. In one aspect, the method includes positioning the substrate surface in a processing chamber and exposing the substrate surface to a soak. A nucleation layer is then deposited on the substrate surface in the same processing chamber by alternately pulsing a tungsten-containing compound and a reducing gas selected from a group consisting of silane, disilane, dichlorosilane and derivatives thereof. A tungsten bulk layer may then be deposited on the nucleation layer using cyclical deposition, chemical vapor deposition, or physical vapor deposition techniques.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. No. 10/268,195, entitled “Method for Depositing Refractory Metal Layers Employing Sequential Deposition Techniques”, filed on Oct. 10, 2002, which claims priority to U.S. Provisional Patent Application Ser. No. 60/328,451, entitled “Method and Apparatus for Depositing Refractory Metal Layers Employing Sequential Deposition Techniques”, filed on Oct. 10, 2001, which are both hereby incorporated by reference in their entirety.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

Embodiments of the invention relate to the processing of semiconductor substrates. More particularly, embodiments of the invention relate to deposition of tungsten layers on semiconductor substrates using ALD techniques.

2. Description of the Related Art

The semiconductor processing industry continues to strive for larger production yields while increasing the uniformity of layers deposited on substrates having larger surface areas. These same factors in combination with new materials also provide higher integration of circuits per unit area of the substrate. As circuit integration increases, the need for greater uniformity and process control regarding layer thickness rises. As a result, various technologies have been developed to deposit layers on substrates in a cost-effective manner, while maintaining control over the characteristics of the layer.

Chemical Vapor Deposition (CVD) is one of the most common deposition processes employed for depositing layers on a substrate. CVD is a flux-dependent deposition technique that requires precise control of the substrate temperature and the precursors introduced into the processing chamber in order to produce a desired layer of uniform thickness. These requirements become more critical as substrate size increases, creating a need for more complexity in chamber design and gas flow technique to maintain adequate uniformity.

A variant of CVD that demonstrates superior step coverage, compared to CVD, is cyclical deposition or atomic layer deposition (ALD). Cyclical deposition is based upon Atomic Layer Epitaxy (ALE) and employs chemisorption techniques to deliver precursor molecules on a substrate surface in sequential cycles. The cycle exposes the substrate surface to a first precursor, a purge gas, a second precursor and the purge gas. The first and second precursors react to form a product compound as a film on the substrate surface. The cycle is repeated to form the layer to a desired thickness.

Formation of film layers at a high deposition rate while providing adequate step coverage are conflicting characteristics often necessitating the sacrifice of one to obtain the other. This conflict is true particularly when refractory metal layers are deposited over gaps or vias during the formation of contacts interconnecting adjacent metallic layers separated by dielectric layers. Historically, CVD techniques have been employed to deposit conductive material such as refractory metals in order to inexpensively and quickly form contacts. Due to the increasing integration of semiconductor circuitry, tungsten has been used based upon superior step coverage. As a result, deposition of tungsten employing CVD techniques enjoys wide application in semiconductor processing due to the high throughput of the process.

Depositing tungsten by traditional CVD methods, however, is attendant with several disadvantages. For example, ALD processes deposit tungsten films into vias containing high aspect ratios (e.g., 20), whereas CVD processes will usually cause similar vias to “pinch-off” and not completely fill. Also, blanket deposition of a tungsten layer on a semiconductor wafer is time-consuming at temperatures below 400° C. The deposition rate of tungsten may be improved by increasing the deposition temperature to, for example, about 500° C. to about 550° C. However, temperatures in this higher range may compromise the structural and operational integrity of the underlying portions of the integrated circuit being formed. Use of tungsten has also frustrated photolithography steps during the manufacturing process as it results in a relatively rough surface having a reflectivity of 70% or less than that of silicon (thickness and wavelength dependent). Further, tungsten has proven difficult to deposit uniformly. Poor surface uniformity typically increases film resistivity.

Therefore, there is a need for an improved technique to deposit conductive layers with good uniformity using cyclical deposition techniques.

SUMMARY OF THE INVENTION

Embodiments of the invention include an improved method for forming a tungsten layer on a substrate surface. In one aspect, the method includes forming a tungsten layer on a substrate surface, comprising positioning the substrate surface in a processing chamber, exposing the substrate surface to a soak for a predetermined time, wherein the soak comprises a soak compound and depositing a nucleation layer in the same processing chamber by alternately pulsing a tungsten-containing compound and a reducing gas, wherein the reducing gas comprises a reductant different than the soak compound.

In another aspect, the method includes forming a tungsten layer on a substrate surface, comprising exposing a substrate surface to diborane at a pressure range from about 1 Torr to about 50 Torr and at a temperature range from about 100° C. to about 400° C., depositing a nucleation layer by alternately pulsing a tungsten-containing compound and silane gas and forming a bulk tungsten deposition film on the nucleation layer.

In yet another aspect, the method includes forming a tungsten layer on a substrate surface, comprising positioning the substrate surface in a processing chamber, exposing the substrate surface to a diborane soak for a predetermined time, depositing a nucleation layer in the same processing chamber by alternately pulsing a tungsten-containing compound and reducing gas, wherein the reducing gas comprises a reductant and forming a bulk tungsten deposition film on the nucleation layer.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 illustrates a process sequence for the formation of a tungsten layer using a cyclical deposition technique according to one embodiment described herein.

FIG. 2 depicts a schematic cross-sectional view of a process chamber useful for practicing the cyclical deposition techniques described herein.

FIG. 3A shows an exemplary integrated processing platform.

FIG. 3B shows another exemplary integrated processing platform.

FIGS. 4A-C show cross sectional views of a via, a nucleated via and a filled via.

FIG. 5 shows a cross sectional view of an exemplary metal oxide gate device formed according to an embodiment of the invention.

FIG. 6 shows a cross sectional view of a conventional DRAM device formed according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention provide an improved process for depositing tungsten films. The process utilizes a cyclical deposition process, such as an atomic layer deposition (ALD) technique and provides tungsten films having significantly improved surface uniformity and production level throughput. In one aspect, the process includes a soak prior to tungsten deposition to activate the underlying substrate surface. Preferably, the underlying surface is exposed to diborane (B₂H₆) or silane (SiH₄) although it is believed that other borane soaks or silane soaks will achieve similar results. In general, the soak occurs in-situ in a range from about 5 seconds to about 90 seconds at similar processing conditions as a subsequent tungsten cyclical deposition process, thereby significantly increasing production throughput.

A “substrate surface”, as used herein, refers to any substrate or material surface formed on a substrate upon which film processing is performed. For example, a substrate surface on which processing can be performed include materials such as silicon, silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Barrier layers, metals or metal nitrides on a substrate surface include titanium, titanium nitride, tungsten nitride, tantalum and tantalum nitride. A substrate surface may also include dielectric materials such as silicon dioxide and carbon doped silicon oxides. Substrates may have various dimensions, such as 200 mm or 300 mm diameter wafers, as well as, rectangular or square panes.

“Atomic layer deposition” or “cyclical deposition” as used herein refers to the sequential introduction of two or more reactive compounds to deposit a layer of material on a substrate surface. The two or more reactive compounds are alternatively introduced into a reaction zone of a processing chamber. Each reactive compound is separated by a time delay to allow each compound to adhere and/or react on the substrate surface. In one aspect, a first precursor or compound A is pulsed into the reaction zone followed by a first time delay. Next, a second precursor or compound B is pulsed into the reaction zone followed by a second delay. During each time delay a purge gas, such as argon, is introduced into the processing chamber to purge the reaction zone or otherwise remove any residual reactive compound or by-products from the reaction zone. Alternatively, the purge gas may flow continuously throughout the deposition process so that only the purge gas flows during the time delay between pulses of reactive compounds. The reactive compounds are alternatively pulsed until a desired film or film thickness is formed on the substrate surface. In either scenario, the ALD process of pulsing compound A, purge gas, compound B and purge gas is a cycle. A cycle can start with either compound A or compound B and continue the respective order of the cycle until achieving a film with the desired thickness.

FIG. 1 illustrates an exemplary process sequence 100 for forming an improved tungsten film according to one embodiment of the present invention. A substrate to be processed is first loaded into a process chamber capable of performing cyclical deposition and the process conditions are adjusted (step 110). The substrate is then exposed to a soak lasting in a range from about 5 seconds to about 90 seconds (step 120). A pulse of a tungsten-containing compound accompanied with a suitable carrier gas is introduced into the processing chamber (step 130). A pulse of gas is then pulsed into the processing chamber (step 140) to purge or otherwise remove any residual tungsten-containing compound or by-products. Next, a pulse of a reducing compound accompanied with a suitable carrier gas is introduced into the processing chamber (step 150). The reducing gas may be the same compound as the gas used for the soak step (step 120) or alternatively, the reducing gas may be a different compound, depending on the product throughput requirements and the device applications. A pulse of gas is then introduced into the processing chamber (step 160) to purge or otherwise remove any residual reducing compound.

Suitable carrier gases or purge gases include helium, argon, nitrogen, hydrogen, forming gas and combinations thereof. Typically, the borane compounds utilize argon or nitrogen as a carrier gas and the silane compounds use hydrogen, argon or nitrogen as the carrier gas.

A “pulse” as used herein is intended to refer to a quantity of a particular compound that is intermittently or non-continuously introduced into a reaction zone of a processing chamber. The quantity of a particular compound within each pulse may vary over time, depending on the duration of the pulse. The duration of each pulse is variable depending upon a number of factors such as, for example, the volume capacity of the process chamber employed, the vacuum system coupled thereto, and the volatility/reactivity of the particular compound itself.

Referring to step 170, after each deposition cycle (steps 130 through 160), a tungsten nucleation layer having a particular thickness will be deposited on the substrate surface. Usually, each deposition cycle forms a layer with a thickness in the range from about 1 Å to about 10 Å. Depending on specific device requirements, subsequent deposition cycles may be needed to deposit tungsten nucleation layer having a desired thickness. As such, a deposition cycle (steps 130 through 160) can be repeated until the desired thickness for the tungsten film is achieved. Thereafter, the process is stopped as indicated by step 180 when the desired thickness is achieved.

Suitable tungsten-containing compounds include tungsten hexafluoride (WF₆), tungsten hexachloride (WCl₆), tungsten carbonyl (W(CO)₆), bis(cyclopentadienyl)tungsten dichloride (Cp₂WCl₂) and mesitylene tungsten tricarbonyl (C₉H₁₂W(CO)₃), as well as derivatives thereof. Suitable reducing compounds and soak compounds include silane compounds, borane compounds and hydrogen. Silane compounds include silane, disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane, tetrachlorosilane, hexachlorodisilane and derivatives thereof, while borane compounds include borane, diborane, triborane, tetraborane, pentaborane, triethylborane and derivatives thereof. Preferred reducing compounds and soak compounds include silane, disilane, diborane and hydrogen.

The substrate surface is exposed to a soak at a temperature in the range from about 100° C. to about 600° C., preferably in the range from about 100° C. to about 400° C., more preferably in the range from about 300° C. to about 350° C. The soak step (step 120) is typically performed at a pressure in the range from about 1 Torr to about 150 Torr, preferably in the range from about 5 Torr to about 90 Torr. In some embodiments, a pressure range is from about 5 Torr to about 20 Torr. In another embodiment, the pressure is about 40 Torr. The soak is usually conducted to the substrate surface for a time in the range from about 5 seconds to about 90 seconds. In one aspect, the soak will last for about 60 seconds or less. In another aspect, the soak will last for about 30 seconds or less. In another aspect, the soak will last for about 10 seconds. The soak includes a soak compound and usually has a carrier gas. The flow rate of the soak compound is generally in the range from about 10 sccm to about 2,000 sccm, preferably in the range from about 50 sccm to about 500 sccm. The flow rate of the carrier gas is generally in the range from about 10 sccm to about 2,000 sccm, preferably in the range from about 50 sccm to about 500 sccm.

In one aspect, diborane is introduced with hydrogen, each having a flow rate between about 50 sccm and about 500 sccm. Preferably, the diborane and hydrogen gases are introduced in a 1:1 volumetric ratio. In another aspect, silane is introduced with hydrogen, each having a flow rate between about 50 sccm and about 500 sccm. Therefore, in step 120, the soak compound is preferably diborane or silane.

The cyclical deposition process or ALD process of FIG. 1 typically occurs at a pressure in the range from about 1 Torr to about 150 Torr, preferably in the range from about 5 Torr to about 90 Torr. In some embodiments, a pressure range is from about 5 Torr to about 20 Torr. In another embodiment, the pressure is about 40 Torr. In one embodiment, the pressure of the soak is maintained for the subsequent ALD process. The temperature of the substrate can be as low as ambient temperature, about 20° C. However, the temperature is usually in the range from about 100° C. to about 600° C., preferably in the range from about 100° C. to about 400° C., more preferably in the range from about 300° C. to about 350° C. In an embodiment, the temperature of the soak is maintained for the subsequent ALD process.

In step 130, the tungsten-containing compound is preferably tungsten hexafluoride and introduced at a rate in the range from about 5 sccm to about 200 sccm. The tungsten-containing compound can be introduced with a carrier gas, such as argon with a flow rate in the range from about 50 sccm to about 1,000 sccm. In step 150, the reducing-compound is preferably diborane or silane and introduced at a rate in the range from about 5 sccm to about 2,000 sccm, preferably in the range from about 50 sccm to about 500 sccm. The reducing-compound can be introduced with a carrier gas, such as hydrogen, with a flow rate in the range from about 50 sccm to about 2,000 sccm. The pulses of a purge gas, preferably argon or nitrogen, at steps 140 and 160, are typically introduced at a rate from about 50 sccm to about 2,000 sccm, preferably at about 500 sccm. Each processing step (steps 130 through 160) lasts from about 0.01 second to about 10 seconds, preferably in the range from about 0.1 second to about 1 second. Longer processing steps, such as about 30 seconds or about 60 seconds, achieve tungsten deposition. However, the throughput is reduced. The specific pressures and times are obtained through experimentation. In one example, a 300 mm diameter wafer needs about twice the flow rate as a 200 mm diameter wafer in order to maintain similar throughput.

FIG. 2 illustrates a schematic, partial cross section of an exemplary processing chamber 16 useful for depositing a tungsten layer according to the embodiments described above. Such a processing chamber 16 is available from Applied Materials, Inc. located in Santa Clara, Calif., and a brief description thereof follows. A more detailed description may be found in commonly assigned U.S. patent application Ser. No. 10/016,300, entitled “Lid Assembly For A Processing System To Facilitate Sequential Deposition Techniques”, filed on Dec. 12, 2001, which is hereby incorporated by reference in its entirety.

Referring to FIG. 2, the processing chamber 16 includes a chamber body 14, a lid assembly 20 for gas delivery and a thermally controlled substrate support member 46. The thermally controlled substrate support member 46 includes a wafer support pedestal 48 connected to a support shaft 48A. The thermally controlled substrate support member 46 may be moved vertically within the chamber body 14 so that a distance between the support pedestal 48 and the lid assembly 20 may be controlled. An example of a lifting mechanism for the support pedestal 48 is described in detail in commonly assigned U.S. Pat. No. 5,951,776, issued Sep. 14, 1999, entitled “Self-Aligning Lift Mechanism”, which is hereby incorporated by reference in it entirety.

The support pedestal 48 includes an embedded thermocouple 50A that may be used to monitor the temperature thereof. For example, a signal from the thermocouple 50A may be used in a feedback loop to control the power applied by a power source 52 to a heater element 52A. The heater element 52A may be a resistive heater element or other thermal transfer device disposed within or disposed in contact with the pedestal 48 utilized to control the temperature thereof. Optionally, the support pedestal 48 may be heated using a heat transfer fluid (not shown).

The support pedestal 48 may be formed from any process-compatible material, including aluminum, aluminum alloys, aluminum nitride and aluminum oxide (Al₂O₃ or alumina) and may also be configured to hold a substrate 49 thereon employing a vacuum, i.e., support pedestal 48 may be a vacuum chuck. Using a vacuum chuck, the support pedestal 48 may include a plurality of vacuum holes (not shown) that are placed in fluid communication with a vacuum source via the support shaft 48A.

The chamber body 14 includes a liner assembly 54 having a cylindrical portion and a planar portion. The cylindrical portion and the planar portion may be formed from any suitable material such as aluminum, ceramic and the like. The cylindrical portion surrounds the support pedestal 48. The cylindrical portion also includes an aperture 60 that aligns with the slit valve opening 44 disposed in a side wall 14B of the housing 14 to allow entry and egress of substrates from the chamber 16.

The planar portion of the liner assembly 54 extends transversely to the cylindrical portion and is disposed against a chamber bottom 14A of the chamber body 14. The liner assembly 54 defines a chamber channel 58 between the chamber body 14 and both the cylindrical portion and planar portion of the liner assembly 54. Specifically, a first portion of channel 58 is defined between the chamber bottom 14A and planar portion of the liner assembly 54. A second portion of channel 58 is defined between the sidewall. 14B of the chamber body 14 and the cylindrical portion of the liner assembly 54. A purge gas is introduced into the channel 58 to minimize unwanted deposition on the chamber walls and to control the rate of heat transfer between the chamber walls and the liner assembly 54.

The chamber body 14 also includes a pumping channel 62 disposed along the sidewalls 14B thereof. The pumping channel 62 includes a plurality of apertures, one of which is shown as a first aperture 62A. The pumping channel 62 includes a second aperture 62B that is coupled to a pump system 18 by a conduit 66. A throttle valve 18A is coupled between the pumping channel 62 and the pump system 18. The pumping channel 62, the throttle valve 18A, and the pump system 18 control the amount of gas flow from the processing chamber 16. The size, number, and position of the apertures 62A in communication with the chamber 16 are configured to achieve uniform flow of gases exiting the lid assembly 20 over the support pedestal 48 having a substrate disposed thereon.

The lid assembly 20 includes a lid plate 20A having a gas manifold 34 mounted thereon. The lid plate 20A provides a fluid tight seal with an upper portion of the chamber body 14 when in a closed position. The gas manifold 34 includes a plurality of control valves 32 (only one shown) to provide rapid and precise gas flow with valve open and close cycles of less than about one second, and in one embodiment, of less than about 0.1 second. The valves 32 are surface mounted, electronically controlled valves. Values that may be utilized are available from Fujikin of Japan.

The lid assembly 20 further includes a plurality of gas sources 68A, 68B, 68C, each in fluid communication with one of the valves 32 through a sequence of conduits (not shown) formed through the chamber body 14, lid assembly 20, and gas manifold 34.

The processing chamber 16 further includes a reaction zone 75 that is formed within the chamber body 14 when the lid assembly 20 is in a closed position. Generally, the reaction zone 75 includes the volume within the processing chamber 16 that is in fluid communication with a wafer 102 disposed therein. The reaction zone 75, therefore, includes the volume downstream of each valve 32 within the lid assembly 20, and the volume between the support pedestal 48 and the lower surface of the lid plate 20. More particularly, the reaction zone 75 includes the volume between the outlet of each valve 32 and an upper surface of the substrate 49.

A controller 70 regulates the operations of the various components of the processing chamber 16. The controller 70 includes a processor 72 in data communication with memory, such as random access memory 74 and a hard disk drive 76 and is in communication with at least the pump system 18, the power source 52, and the valves 32.

Software routines are executed to initiate process recipes or sequences. The software routines, when executed, transform the general purpose computer into a specific process computer that controls the chamber operation so that a chamber process is performed. For example, software routines may be used to precisely control the activation of the electronic control valves for the execution of process sequences according to aspects of the present invention. Alternatively, the software routines may be performed in hardware, as an application specific integrated circuit or other type of hardware implementation, or a combination of software or hardware.

Process Integration

A tungsten nucleation layer as described above has shown particular utility when integrated with traditional bulk fill techniques to form features with excellent film properties. An integration scheme can include ALD or cyclical deposition nucleation with bulk fill chemical vapor deposition (CVD) or physical vapor deposition (PVD) processes. Integrated processing systems capable of performing such an integration scheme include an Endura®, Endura SL®, Centura® and Producer® processing systems, each available from Applied Materials, Inc. located in Santa Clara, Calif. Any of these systems can be configured to include at least one cyclical deposition chamber for depositing the nucleation layer and at least one CVD chamber or PVD chamber for bulk fill.

FIG. 3A is a schematic top-view diagram of an exemplary multi-chamber processing system 300. A similar multi-chamber processing system is disclosed in commonly assigned U.S. Pat. No. 5,186,718, entitled “Staged Vacuum Wafer Processing System and Method,” issued on Feb. 16, 1993, which is incorporated by reference herein. The system 300 generally includes load lock chambers 302, 304 for the transfer of substrates into and out from the system 300. Typically, since the system 300 is under vacuum, the load lock chambers 302, 304 may “pump down” the substrates introduced into the system 300. A first robot 310 may transfer the substrates between the load lock chambers 302, 304, and a first set of one or more substrate processing chambers 312, 314, 316, 318 (four are shown). Each processing chamber 312, 314, 316, 318, can be outfitted to perform a number of substrate processing operations such as cyclical layer deposition, CVD, PVD, etch, pre-clean, de-gas, orientation and other substrate processes. The first robot 310 also transfers substrates to/from one or more transfer chambers 322, 324.

The transfer chambers 322, 324, are used to maintain ultrahigh vacuum conditions while allowing substrates to be transferred within the system 300. A second robot 330 may transfer the substrates between the transfer chambers 322, 324 and a second set of one or more processing chambers 332, 334, 336, 338. Similar to processing chambers 312, 314, 316, 318, the processing chambers 332, 334, 336, 338 can be outfitted to perform a variety of substrate processing operations, such as cyclical deposition, CVD, PVD, etch, pre-clean, de-gas, and orientation, for example. Any of the substrate processing chambers 312, 314, 316, 318, 332, 334, 336, 338 may be removed from the system 300 if not necessary for a particular process to be performed by the system 300.

In one arrangement, each processing chamber 332 and 338 may be a cyclical deposition chamber adapted to deposit a nucleation layer; each processing chamber 334 and 336 may be a cyclical deposition chamber, a chemical vapor deposition chamber, or a physical vapor deposition chamber adapted to form a bulk fill deposition layer; each processing chamber 312 and 314 may be a physical vapor deposition chamber, a chemical t vapor deposition chamber, or a cyclical deposition chamber adapted to deposit a dielectric layer; and each processing chamber 316 and 318 may be an etch chamber outfitted to etch apertures or openings for interconnect features. This one particular arrangement of the system 300 is provided to illustrate the invention and should not be used to limit the scope of the invention.

Another integrated system may include nucleation deposition as well as bulk fill deposition in a single chamber. A chamber configured to operate in both a cyclical deposition mode as well as a conventional CVD mode can be used. One example of such a chamber is described in commonly assigned U.S. patent application Ser. No. 10/016,300, filed on Dec. 12, 2001, which is incorporated herein by reference.

In another integration scheme, one or more cyclical deposition nucleation chambers are integrated onto a first processing system while one or more bulk layer deposition chambers are integrated onto a second processing system. In this configuration, substrates are first processed in the first system where a nucleation layer is deposited on a substrate. Thereafter, the substrates are moved to the second processing system where bulk deposition occurs.

FIG. 3B is a schematic top-view diagram of an exemplary multi-chamber processing system 350. The system 350 generally includes load lock chambers 352, 354 for the transfer of substrates into and out from the system 350. Typically, since the system 350 is under vacuum, the load lock chambers 352, 354 may “pump down” the substrates introduced into the system 350. A robot 360 may transfer the substrates between the load lock chambers 352, 354, and substrate processing chambers 362, 364, 366, 368, 370 and 372. Each processing chamber 362, 364, 366, 368, 370 and 372 can be outfitted to perform a number of substrate processing operations such as cyclical layer deposition, CVD, PVD, etch, pre-clean, de-gas, heat, orientation and other substrate processes. The robot 360 also transfers substrates to/from a transfer chamber 356. Any of the substrate processing chambers 362, 364, 366, 368, 370 and 372 may be removed from the system 350 if not necessary for a particular process to be performed by the system 350.

In one arrangement, each processing chamber 364 and 370 may be a cyclical deposition chamber adapted to deposit a nucleation layer; each processing chamber 366 and 368 may be a cyclical deposition chamber, a chemical vapor deposition chamber or a physical vapor deposition chamber adapted to form a bulk fill deposition layer. This one particular arrangement of the system 350 is provided to illustrate the invention and should not be used to limit the scope of the invention.

Alternatively, a carousel type batch processing system having a plurality of stations in a single chamber can be adapted to incorporate nucleation and bulk layer deposition into a single processing system. In such a processing system a purge gas curtain, such as an argon gas curtain, can be established between each station creating a micro or mini environment at each station. The substrates are loaded into the system sequentially and then rotated through each station and processed at least partially at each station. For example, a substrate may be exposed to a cyclical deposition nucleation step at a first station and then to partial bulk fill CVD steps at each of the subsequent stations. Alternatively, nucleation may occur at more than one station and bulk fill may occur at one or more stations. Still further, the nucleation layer and the bulk layer may be deposited in separate carousel type systems. In another aspect, the soak and the nucleation steps are completed in one carousel while the bulk steps are done on another carousel, wherein both carousels are part of the same process system. Each platen can be temperature controlled to provide at least some process control at each station. However, the process pressure typically remains the same between stations because the stations are housed in a single chamber. Some pressure control may be available in a micro or mini environment present at each station due to the inert gas curtain.

Regardless of the integration scheme, the nucleation layer is typically deposited to a thickness ranging from about 10 Å to about 200 Å and the bulk fill has a thickness in the range from about 100 Å to about 10,000 Å, preferably in the range from about 1,000 Å to about 5,000 Å. However, the thickness of these films can vary depending on the feature sizes and aspect ratios of a given application. Accordingly, the films are suitably sized to accommodate the geometries of a given application. The following are some exemplary geometries and applications that can benefit from a nucleation layer deposited according to embodiments described herein. The following descriptions are intended for illustrative purposes only, and are not intended to limit the uses of the present invention.

FIGS. 4A-C show cross sectional views of a semiconductor feature that an embodiment of the process is utilized to fill a via 460. In FIG. 4A, the substrate 450 includes at least one via 460. A barrier layer 451, such as titanium nitride, is deposited by ALD, CVD or PVD techniques to the substrate 450 with via 460. Prior to the nucleation of a tungsten layer 452, as depicted in FIG. 4B, a soak is administered to barrier layer 451. The soak process renders the sidewalls, of the barrier layer 451 within the via 460, to adhere and grow the tungsten layer 452 at about the same rate as the barrier layer 451 outside the via 460. When the soak process is omitted, growth of tungsten layer 452 on the sidewalls is not constant with respect to the growth of tungsten layer 452 outside the via 460. Once nucleation of tungsten layer 452 has been deposited, then the bulk fill of tungsten layer 452 is progressed to fill the via 460, as demonstrated in FIG. 4C. In one embodiment, an ALD process is continued after deposition of a tungsten nucleation layer to deposit the tungsten bulk fill layer.

Tungsten Metal Gate

FIG. 5 shows a cross sectional view of an exemplary metal oxide gate device 400 utilizing a nucleation layer deposited according to embodiments described herein. The device 400 generally includes an exposed gate 410 surrounded by spacers 416 and silicon source/drain areas 420 formed within a substrate surface 412. The spacers 416 typically include an oxide, such as silicon dioxide, or a nitride, such as silicon nitride.

The metal gate 410 includes an oxide layer 411, a polysilicon layer 414, a titanium nitride barrier layer 415 and a tungsten layer 422. The oxide layer 411 separates the substrate 412 from the polysilicon layer 414. The oxide layer 411 and the polysilicon layer 414 are deposited using conventional deposition techniques.

The titanium nitride barrier layer 415 is deposited on the polysilicon layer 414. The titanium nitride barrier layer 415 may be a bi-layer stack formed by depositing a PVD titanium layer followed by a CVD titanium nitride layer. The titanium nitride barrier layer 415 may also be deposited using a cyclical deposition technique, such as the process shown and described in commonly assigned and co-pending U.S. patent application Ser. No. 10/032,293, filed on Dec. 21, 2001, entitled “Chamber Hardware Design for Titanium Nitride Atomic Layer Deposition”, which is incorporated by reference herein.

A soak process is administered to the substrate surface. The soak includes a silane compound or a borane compound along with at least one carrier gas. A preferred silane compound is silane, a preferred borane compound is diborane and a preferred carrier gas is either hydrogen and/or argon. In one aspect, silane has a flow rate in the range from about 25 sccm to about 500 sccm and hydrogen has a flow rate in the range from about 200 sccm to about 700 sccm. The soak is conducted at a temperature in the range from about 100° C. to about 400° C., preferably at about 300° C., a pressure in the range from about 1 Torr to about 120 Torr, preferably at about 30 Torr to about 120 Torr and a period of time from 5 seconds to about 90 seconds. In another aspect, diborane has a flow rate in the range from about 25 sccm to about 500 sccm and hydrogen and/or argon has a flow rate in the range from about 200 sccm to about 700 sccm. The soak is conducted at a temperature in the range from about 100° C. to about 400° C., preferably at about 300° C., a pressure in the range from about 1 Torr to about 120 Torr, preferably at about 1 Torr to about 50 Torr, and a period of time from 5 seconds to about 90 seconds, preferably less than about 60 seconds.

A nucleation layer 417 is then cyclically deposited over the barrier layer 415 following treatment of the substrate surface with a soak process. In one aspect, the nucleation layer 417 is cyclically deposited using alternating pulses of tungsten hexafluoride and diborane. The tungsten hexafluoride is pulsed at a rate of between about 1 sccm and about 100 sccm, such as between about 5 sccm and about 50 sccm, for about 0.3 seconds. A carrier gas, such as argon, is provided along with the tungsten hexafluoride at a rate of about 100 sccm to about 1,000 sccm, such as between about 100 sccm to about 500 sccm. The diborane is pulsed at a rate of about 50 sccm and about 1,000 sccm, such as between about 400 sccm and about 600 sccm, for about 0.3 seconds. A carrier gas, such as hydrogen, is provided along with the diborane at a rate between about 50 sccm to about 500 sccm, such as between about 100 sccm to about 300 sccm. The substrate is maintained at a temperature between about 100° C. and about 400° C., preferably at about 300° C., at a chamber pressure between about 1 Torr and about 120 Torr, preferably between about 1 Torr and about 50 Torr. In between pulses of the tungsten hexafluoride and the diborane, argon is pulsed for about 0.5 seconds to purge or otherwise remove any reactive compounds from the processing chamber.

In another aspect, the nucleation layer 417 is cyclically deposited using alternating pulses of tungsten hexafluoride and silane. The tungsten hexafluoride is pulsed as described above with argon for about 0.5 seconds. The silane is pulsed at a rate of about 1 sccm to about 100 sccm, such as between about 5 sccm to about 50 sccm, for about 0.5 seconds. A carrier gas, such as hydrogen, is provided along with the silane at a rate of about 100 sccm and about 1,000 sccm, such as between about 100 sccm and about 500 sccm. Argon is pulsed at a rate of about 100 sccm to about 1,000 sccm, such as between about 300 sccm to about 700 sccm, for about 0.5 seconds between the pulses of the tungsten hexafluoride and the pulses of silane. The substrate is maintained at a temperature between about 100° C. and about 400° C., preferably at about 300° C., at a chamber pressure between about 1 Torr and about 30 Torr.

A nucleation layer formed by alternating pulses of tungsten hexafluoride and a reducing compound with a soak treatment has advantages over a nucleation layer formed by alternating pulses of tungsten hexafluoride and the same reducing compound without the prior soak. The tungsten film shows less stress for the integrated film, as well as, less fluorine content at the interface of the nucleation layer. Also, the nucleation layer deposited post a soak treatment has higher uniformity coverage and is deposited quicker due to a reduced incubation period.

A tungsten bulk fill 422 is then deposited on the tungsten nucleation layer 417. Although any metal deposition process, such as conventional chemical vapor deposition or physical vapor deposition, may be used, the tungsten bulk fill 422 may be deposited by alternately adsorbing a tungsten-containing compound and a reducing compound as described above. A more detailed description of tungsten deposition using a cyclical depositon technique may be found in commonly assigned U.S. patent application Ser. No. 10/016,300, entitled “Lid Assembly For A Processing System To Facilitate Sequential Deposition Techniques”, filed on Dec. 12, 2001 and in commonly assigned U.S. patent application Ser. No. 10/082,048, entitled “Deposition Of Tungsten Films For Dynamic Random Access Memory (DRAM) Application”, filed on Feb. 20, 2002, which are both incorporated herein by reference. Fewer volcanos appear on the surface of the tungsten film deposited utilizing a soak, as compared to tungsten films deposited without exploiting a soak, post tungsten bulk-fill.

Following deposition, the top portion of the resulting structure 400 may be planarized. A chemical mechanical polishing (CMP) apparatus may be used, such as the Mirra™ System available from Applied Materials, Santa Clara, Calif., for example. Portions of the tungsten bulk fill 422 are removed from the top of the structure leaving a fully planar surface. Optionally, the intermediate surfaces of the structure may be planarized between the depositions of the subsequent layers described above.

FIG. 6 is a cross sectional view of a conventional DRAM device having a transistor 520 positioned adjacent a top portion of a trench capacitor 530. The access transistor 520 for the DRAM device 510 is positioned adjacent a top portion of the trench capacitor 530. Preferably, the access transistor 520 comprises an n-p-n transistor having a source region 522, a gate region 524 and a drain region 526. The gate region 524 is a P-doped silicon epi-layer disposed over the P+ substrate. The source region 522 of the access transistor 520 is an N+ doped material disposed on a first side of the gate region 524 and the drain region 526 is an N+ doped material disposed on a second side of the gate region 524, opposite the source region 522.

The source and drain regions 522, 524 may be connected to a tungsten plug 560. Each tungsten plug 560 includes a titanium liner 562, a tungsten nucleation layer 564, and a bulk tungsten fill 566. The titanium liner 562 may be a bi-layer stack comprising PVD titanium followed by CVD titanium nitride. Alternatively, the titanium liner 562 may be a bi-layer stack comprising ALD deposited titanium followed by ALD deposited titanium nitride. The tungsten nucleation layer 564 is formed using the soak and cyclical deposition techniques as described above. The tungsten bulk fill 566 may be deposited using any conventional deposition techniques, including ALD, CVD and PVD.

The trench capacitor 530 generally includes a first electrode 532, a second electrode 534 and a dielectric material 536 disposed therebetween. The P+ substrate serves as a first electrode 532 of the trench capacitor 530 and is connected to a ground connection 541. A trench 538 is formed in the P+ substrate and filled with a heavily doped N+ polysilicon that serves as the second electrode 534 of the trench capacitor 530. The dielectric material 536 is disposed between the first electrode 532 (i.e., P+ substrate) and the second electrode 534 (i.e., N+ polysilicon).

The trench capacitor 530 also includes a first tungsten nitride barrier layer 540 disposed between the dielectric material 536 and the first electrode 532. Preferably, a second tungsten nitride barrier layer 542 is disposed between the dielectric material 536 and the second electrode 534. Alternatively, the barrier layers 540, 542 are a combination film, such as W/WN.

Although the above-described DRAM device utilizes an n-p-n transistor, a P+ substrate as a first electrode, and an N+ polysilicon as a second electrode of the capacitor, other transistor designs and electrode materials are contemplated by the present invention to form DRAM devices. Additionally, other devices, such as crown capacitors for example, are contemplated by the present invention.

EXAMPLES

Substrates were prepared with a barrier layer prior to a soak and subsequent tungsten deposition. A titanium (Ti) layer was deposited by PVD on a 200 mm substrate surface to a thickness of about 100 Å for Examples 1-4. A titanium nitride (TiN) layer was deposited on the Ti layer using an atomic layer deposition (ALD) process to a thickness of about 80 Å to form a Ti/TiN barrier layer.

Example 1 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: B²H⁶;

Pressure: about 5 Torr;

Temperature: about 300° C.;

Flow rates: 150 sccm B₂H₆ and 150 sccm H₂; and

Duration: about 10 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and B₂H₆;

Pressure: about 5 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 20 sccm WF₆ and 300 sccm Ar;

-   -   pulse B: 150 sccm B₂H₆ and 150 sccm H₂;     -   Ar-purge: 500 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.2 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.2 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 50 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 2 percent.

Example 2 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: SiH₄;

Pressure: about 90 Torr;

Temperature: about 350° C.;

Flow rates: 75 sccm SiH₄ and 500 sccm H₂; and

Duration: about 30 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 10 Torr;

Temperature: about 350° C.;

Flow rates: pulse A: 30 sccm WF₆ and 300 sccm Ar;

-   -   pulse B: 20 sccm SiH₄ and 300 sccm H₂;     -   Ar purge: 500 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.3 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.3 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 100 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 4 percent.

Example 3 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: SiH₄;

Pressure: about 90 Torr;

Temperature: about 300° C.;

Flow rates: 75 sccm SiH₄ and 500 sccm H₂; and

Duration: about 60 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 20 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 20 sccm WF₆ and 300 sccm Ar;

-   -   pulse B: 15 sccm SiH₄ and 300 sccm H₂;     -   Ar purge: 500 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.5 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.5 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 75 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 3 percent.

Example 4 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: B₂H₆;

Pressure: about 15 Torr;

Temperature: about 300° C.;

Flow rates: 150 sccm B₂H₆ and 150 sccm H₂; and

Duration: about 10 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 15 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 20 sccm WF₆ and 300 sccm Ar;

-   -   pulse B: 15 sccm SiH₄ and 300 sccm H₂;     -   Ar purge: 500 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.3 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.3 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 50 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 1 percent.

In another set of examples, substrates were prepared with a barrier layer prior to a soak and subsequent tungsten deposition. A titanium (Ti) layer was deposited by PVD on a 300 mm substrate surface to a thickness of about 100 Å for Examples 5-8. A titanium nitride (TiN) layer was deposited on the Ti layer using an atomic layer deposition (ALD) process to a thickness of about 80 Å to form a Ti/TiN barrier layer.

Example 5 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: B₂H₆;

Pressure: about 5 Torr;

Temperature: about 300° C.;

Flow rates: 200 sccm B2H₆ and 500 sccm Ar; and

Duration: about 15 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and B₂H₆;

Pressure: about 5 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 50 sccm WF₆ and 600 sccm Ar;

-   -   pulse B: 150 sccm B₂H₆ and 500 sccm Ar;     -   Ar-purge: 1,000 sccm;

Cycle duration: Ar-purge: 0.3 seconds;

-   -   pulse A: 0.2 seconds;     -   Ar-purge: 0.3 seconds; and     -   pulse B: 0.3 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 50 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 2 percent.

Example 6 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: SiH₄;

Pressure: about 90 Torr;

Temperature: about 350° C.;

Flow rates: 200 sccm SiH₄; 1,000 sccm H₂ and 1,000 sccm Ar;

Duration: about 10 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 90 Torr;

Temperature: about 350° C.;

Flow rates: pulse A: 50 sccm WF₆ and 600 sccm Ar;

-   -   pulse B: 30 sccm SiH₄ and 500 sccm Ar;     -   Ar purge: 1,000 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.3 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.3 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 100 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 4 percent.

Example 7 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: SiH₄;

Pressure: about 90 Torr;

Temperature: about 300° C.;

Flow rates: 150 sccm SiH₄ and 1,000 sccm H₂; and

Duration: about 60 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 20 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 40 sccm WF₆ and 600 sccm Ar;

-   -   pulse B: 30 sccm SiH₄ and 600 sccm H₂;     -   Ar purge: 1,000 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.5 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.5 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 75 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 3 percent.

Example 8 The Substrate Surface was Exposed to a Soak Under the Following Conditions

Reagent: B₂H₆;

Pressure: about 15 Torr;

Temperature: about 300° C.;

Flow rates: 300 sccm B₂H₆ and 300 sccm H₂; and

Duration: about 10 seconds.

Next, a tungsten nucleation layer was formed on the barrier layer using an ALD process under the following conditions:

Reagents: WF₆ and SiH₄;

Pressure: about 15 Torr;

Temperature: about 300° C.;

Flow rates: pulse A: 40 sccm WF₆ and 600 sccm Ar;

-   -   pulse B: 30 sccm SiH₄ and 600 sccm H₂;     -   Ar purge: 1,000 sccm;

Cycle duration: Ar-purge: 0.5 seconds;

-   -   pulse A: 0.3 seconds;     -   Ar-purge: 0.5 seconds; and     -   pulse B: 0.3 seconds.

The cycle was repeated until the nucleation layer had a thickness of about 50 Å. Finally, a bulk tungsten layer was deposited on the nucleation layer using CVD to a thickness of about 2,500 Å. The resulting tungsten bulk fill film exhibited a uniformity variance of less than about 1 percent.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A method for forming a tungsten layer on a substrate surface, comprising: positioning the substrate surface in a processing chamber; exposing the substrate surface to a soak for a predetermined time, wherein the soak comprises a soak compound; and depositing a nucleation layer in the same processing chamber by alternately pulsing a tungsten-containing compound and a reducing gas,-wherein the reducing gas comprises a reductant different than the soak compound.
 2. The method of claim 1, wherein the reductant is selected from the group consisting of hydrogen, silane, disilane, trisilane, dichlorosilane, borane, diborane, derivatives thereof, and combinations thereof.
 3. The method of claim 2, wherein the nucleation layer is deposited by alternately pulsing tungsten hexafluoride and silane.
 4. The method of claim 2, wherein the nucleation layer is deposited by alternately pulsing tungsten hexafluoride and diborane.
 5. The method of claim 4, wherein the nucleation layer has a thickness in a range from about 10 Å to about 200 Å.
 6. The method of claim 2, wherein the tungsten-containing compound is selected from the group consisting of tungsten hexafluoride and tungsten carbonyl.
 7. The method of claim 6, wherein the soak compound is selected from the group consisting of hydrogen, borane, diborane, hydrogen, silane, disilane, trisilane, dichlorosilane, derivatives thereof and combinations thereof.
 8. The method of claim 7, wherein exposing the substrate surface to the soak for the predetermined time is in a range from about 5 seconds to about 90 seconds.
 9. The method of claim 1, further comprising forming a bulk tungsten deposition film on the nucleation layer using atomic layer deposition, chemical vapor deposition or physical vapor deposition techniques.
 10. The method of claim 7, wherein exposing the substrate surface to the soak is at a temperature in a range from about 100° C. to about 400° C.
 11. The method of claim 7, wherein the substrate surface comprises titanium nitride.
 12. A method for forming a tungsten layer on a substrate surface, comprising: exposing a substrate surface to diborane at a pressure range from about 1 Torr to about 50 Torr and at a temperature range from about 100° C. to about 400° C.; depositing a nucleation layer by alternately pulsing a tungsten-containing compound and silane gas; and forming a bulk tungsten deposition film on the nucleation layer.
 13. The method of claim 12, wherein exposing the substrate surface to diborane and depositing the nucleation layer occurs in the same chamber.
 14. The method of claim 13, wherein the nucleation layer has a thickness in a range from about 10 Å to about 200 Å.
 15. The method of claim 14, wherein the bulk tungsten deposition film has a thickness in a range from about 100 Å to about 5,000 Å.
 16. The method of claim 13, wherein exposing the substrate surface to diborane for a predetermined time is in a range from about 5 seconds to about 90 seconds.
 17. The method of claim 12, wherein the substrate surface comprise a barrier layer selected from the group consisting of titanium, titanium nitride, tungsten nitride, tantalum and tantalum nitride.
 18. A method for forming a tungsten layer on a substrate surface, comprising: positioning the substrate surface in a processing chamber; exposing the substrate surface to a diborane soak for a predetermined time; depositing a nucleation layer in the same processing chamber by alternately pulsing a tungsten-containing compound and a reducing gas, wherein the reducing gas comprises a reductant; and forming a bulk tungsten deposition film on the nucleation layer.
 19. The method of claim 18, wherein the nucleation layer has a thickness in a range from about 10 Å to about 200 Å.
 20. The method of claim 19, wherein the bulk tungsten deposition film has a thickness in a range from about 100 Å to about 5,000 Å.
 21. The method of claim 19, wherein the tungsten-containing compound is selected from the group consisting of tungsten hexafluoride and tungsten carbonyl.
 22. The method of claim 21, wherein exposing the substrate surface to the diborane soak for the predetermined time is in a range from about 5 seconds to about 90 seconds.
 23. The method of claim 22, wherein exposing the substrate surface to the diborane soak is at a temperature in a range from about 100° C. to about 400° C.
 24. The method of claim 18, wherein the reductant is selected from the group consisting of hydrogen, silane, disilane, trisilane, dichlorosilane, borane, diborane, derivatives thereof, and combinations thereof.
 25. The method of claim 24, wherein the tungsten-containing compound is tungsten hexafluoride and the reductant is silane.
 26. The method of claim 24, wherein the tungsten-containing compound is tungsten hexafluoride and the reductant is diborane.
 27. A method for forming a tungsten layer on a substrate surface, comprising: positioning the substrate surface in a processing chamber; exposing the substrate surface to a soak for a predetermined time, wherein the soak comprises a soak compound selected from the group consisting of hydrogen, borane, diborane, hydrogen, silane, disilane, trisilane, dichlorosilane, derivatives thereof and combinations thereof; and depositing a nucleation layer in the same processing chamber by alternately pulsing a tungsten-containing compound and a reducing gas, wherein the reducing gas comprises a reductant different than the soak compound.
 28. The method of claim 27, wherein the reductant is selected from the group consisting of hydrogen, silane, disilane, trisilane, dichlorosilane, borane, diborane, derivatives thereof, and combinations thereof.
 29. The method of claim 28, wherein the nucleation layer is deposited by alternately pulsing tungsten hexafluoride and silane.
 30. The method of claim 28, wherein the nucleation layer is deposited by alternately pulsing tungsten hexafluoride and diborane.
 31. The method of claim 30, wherein the nucleation layer has a thickness in a range from about 10 Å to about 200 Å.
 32. The method of claim 28, wherein the tungsten-containing compound is selected from the group consisting of tungsten hexafluoride and tungsten carbonyl.
 33. The method of claim 32, wherein exposing the substrate surface to the soak for the predetermined time is in a range from about 5 seconds to about 90 seconds.
 34. The method of claim 28, further comprising forming a bulk tungsten deposition film on the nucleation layer using atomic layer deposition, chemical vapor deposition or physical vapor deposition techniques.
 35. The method of claim 32, wherein exposing the substrate surface to the soak is at a temperature in a range from about 100° C. to about 400° C.
 36. The method of claim 32, wherein the substrate surface comprises titanium nitride. 